Selecting Pome Fruit Crops and Varieties - Growing Organic Orchard Fruits - page 160

Not all combinations of apple varieties provide effective pollination. 'Cort-
land' and 'Early McIntosh' will not effectively pollinate each other, for ex-
ample. Some varieties produce infertile pollen and cannot be used as pollin-
izers, as shown in the box at right. Very early-blooming and very late-bloom-
ing varieties do not effectively cross-pollinate each other because the flower-
ing periods do not overlap sufficiently. Examples are shown in table 5.1 ➔ .
Closely related varieties also tend to be poor cross-pollinizers. Strains
developed from 'McIntosh', 'Red Delicious', and 'Golden Delicious' (including
'Jonagold') tend to be poor cross-pollinizers with their parents or other
strains derived from those parents. For example, 'Nured McIntosh', 'Jonamac',
and 'Mor-Spur McIntosh' should not be used to cross-pollinate one another.
Other than the exceptions described above, most combinations of do-
mestic apple varieties typically cross-pollinate well. Crab apples can serve
as effective cross-pollinizers for domestic apples and are especially valuable
in large, commercial orchards where varieties are planted in solid blocks to
simplify cultural practices and harvest. Check with your nursery before mak-
ing final choices to ensure that the trees you plant will effectively cross-pol-
linate each other.
In general, make sure you have a pollinizer within 50 feet of every tree.
If your orchard has multiple tree rows, include pollinizers in every row and
stagger their locations in every other row to form a repeating triangular pat-
tern of pollinizers. When space is very limited, bud or graft a pollinizing vari-
ety onto your tree or trees.
TABLE 5.1
Suitability of Apple Varieties for Cross-Pollination
Listed below are common early- and late-blooming apple varieties
whose blooms do not overlap sufficiently to provide effective cross-pol-
lination. Varieties in each group are suitable cross-pollinizers for oth-